[ ir-i-vur-suh-buh l ]
/ ˌɪr ɪˈvɜr sə bəl /


not reversible; incapable of being changed: His refusal is irreversible.

Nearby words

  1. irretentive,
  2. irretraceable,
  3. irretrievable,
  4. irreverence,
  5. irreverent,
  6. irreversible pulpitis,
  7. irrevocable,
  8. irrigable,
  9. irrigate,
  10. irrigation

Origin of irreversible

First recorded in 1620–30; ir-2 + reversible

Related formsir·re·vers·i·bil·i·ty, ir·re·vers·i·ble·ness, nounir·re·vers·i·bly, adverb Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019

Examples from the Web for irreversible

British Dictionary definitions for irreversible


/ (ˌɪrɪˈvɜːsəbəl) /


not able to be reversedthe irreversible flow of time
not able to be revoked or repealed; irrevocable
chem physics capable of changing or producing a change in one direction onlyan irreversible reaction
thermodynamics (of a change, process, etc) occurring through a number of intermediate states that are not all in thermodynamic equilibrium
Derived Formsirreversibility or irreversibleness, nounirreversibly, adverb

Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012

Word Origin and History for irreversible



1620s, from assimilated form of in- (1) "not, opposite of" + reversible. Related: Irreversibly.

Online Etymology Dictionary, © 2010 Douglas Harper